connection problem with MCB900

pak · January 28, 2007, 02:59:38 AM

Hi,
I have MCB900 with 89LPC936. It is working fine for three months. One day, I tried to use "Device Configuration" from ISP menu. From 89LPC9xx Configuration Dialog box, I changed Clock: to External Clock on XTAL1 and pressed Reprogram button. After that, I have lost connection with Flash Magic. What should I do? Please help .

Thank in advance,
pak

Andy Ayre · January 29, 2007, 07:37:38 AM

Did you try applying an external clock to XTAL1? Without it your device won't do anything.

pak · January 30, 2007, 12:41:57 AM

Hi Andy,
I put a crystal (11.0592MHz) on MCB900. But I did not uncheck ISP check box. What do you suggest in that case? Is ISP corrupted?

Thanks anyway,
pak

Je Gold · January 30, 2007, 06:08:24 AM

Yes, when using ISP (which uses the UART) which requires a oscillator - either internal RC or external Xtal.

When you flash program the LPC936 for external Xtal... Yes, you do need an external Xtal to get the LPC936 oscllator path going.

When this happens. You need.................

XTAL + the two xtal oscillator capacitors.. C5 = C6 = 22pF otherwise the the Xtal will not oscillate.

ALSO
My limited Understanding is ICP.... which requires a little more hardware to program the LPC936 does not need external Xtal and switches to internal RC.... so you always have control.... this yet to be verified by testing...

Joe

pak · January 30, 2007, 08:10:27 PM

Hi Gold,
Thank for suggestion, So ICP is more reliable than ISP? Is it safety to use ICP without corruption of ISP on LPC that programmed by factory? Actually, I do not like to have problem with flashing LPC device so I looking for safe way to flash it.
I used to flash PIC microcontroller there is no worry at all. Is it possible to get safe way to flash LPC devices without any problem?

Thanks,
pak

erikm · January 31, 2007, 06:08:21 AM

So ICP is more reliable than ISP

ISP is totally reliable when the rules are followed. I have used ISP extensively and never used ICP and have yet to have a failure (save one where I had to call myself an idiot)

That failure made me develop NoTouch and 'the backdoor' and I have since had none, zero, nada problems.

Erik

pak · January 31, 2007, 09:42:26 AM

Hi Erik,
Thank for solution of ISP corruption. I have to study your "touchless" theory and will discuss with you later.

thanks,
pak

Je Gold · February 01, 2007, 05:51:36 AM

The problem with NoTouch/Touchless is - If your NoTouch code does not work when you program it CAN NOT be recovered by NoTouch code... only "hardware" entry methods will work... ISP or ICP.

There are no difinative NoTouch articles for P89LPC93x but there are for P89C51 and P89C66x.

NoTouch theory as coined by Erik is...

-on some event in your code.... say 'Looking for a AAA' from the UART.... jump to the bootloader 0x1FFFh - this puts you in to ISP mode ready for Flashmagic to work.

ICP hardware entry will allow you to recover the LPC936 from all events and it has more "physical" control over the micro.

Once once you get your NoTouch code working... you can throw away the ICP and ISP hardware.... but during developpment - if your code breaks (eg stuck in a loop and you can't execute NoTouch)..... you will need to use ICP or ISP to recover the micro.

Joe

erikm · February 01, 2007, 01:20:13 PM

Once once you get your NoTouch code working... you can throw away the ICP and ISP hardware.... but during developpment - if your code breaks (eg stuck in a loop and you can't execute NoTouch)..... you will need to use ICP or ISP to recover the micro.

That is why I invented "the backdoor" have a read.

I know that all "literature" te NoTouch etc is in the P89C documents, but reading them and transferring the ideas will take you no more than 5 minutes.

Erik